1. Field of the Invention
This invention relates to a method for making crosslinked polyvinylpyrrolidone (PVP) polymers by reaction between epoxide-containing PVP copolymers and tertiary-amine-containing PVP copolymers in solution at a predetermined temperature.
2. Description of the Prior Art
Merijan, in U.S. Pat. No. 3,563,968, described the preparation of functional graft homopolymers of vinyl lactams, e.g. vinyl pyrrolidone, by reaction of polyvinylpyrrolidone with allyl amine or allyl alcohol in ethanol solvent in a bomb reactor at 130.degree.-140.degree. C.
Kitcheil, in U.S. Pat. Nos. 4,692,328 and 4,772,484, disclosed the chemical crosslinking reaction of the Merijan functional graft homopolymers with glutaraldehyde to form a gel which was useful in biological applications.
PVP and PVP copolymers also have been physically crosslinked using E-beam or gamma radiation.
However, it would be of advantage to provide a simple method of crosslinking a mixture of stable, crosslinkable vinyl lactam polymers at a predetermined pH, without further condensation with glutaraldehyde, or the necessity of expensive radiation equipment.